Blocking access to personal Gmail accounts in proxy server

[jatkin]

Hi!

I'm looking for a solid method of blocking access to employees logging into their personal Gmail accounts, while not impacting their ability to log into their Google Workspace account. Unfortunately, Google combines URLs for Gmail and Google Workspace (!!!), making it difficult to control access. There doesn't appear to be documentation on it either. Our temp solution became undone, to our lack of knowledge, when Google recently migrated from v2 to v3, and changed who knows what or how many URLs affecting the login process.